Effect of perchlorate ion on the textural and catalytic activity of zirconia

Synthesis and physico-chemical characterization of hydrous zirconia gel wer e carried out. The perchlorate sorption properties of hydrous zirconia were found to be appreciable and a loading of about 9 wt% was possible in an eq uilibrium solution of 0.1 M HClO4. Formation of perchlorated zirconia has b een investigated using XRD, TG/DTA and FTIR. Nitrogen adsorption desorption isotherms at liquid nitrogen temperature were used to explore the surface area and porosity of the samples. The nitration of chlorobenzene was used a s the test reaction. It was observed that finely divided zirconia with meso porous texture can be prepared using preshaped precipitating medium. The XR D patterns revealed that perchlorate ion stabilizes the tetragonal phase of zirconia. TG/DTA and FTIR studies supported the presence of perchlorate mo iety in the sample. The surface acidity measurement using different organic bases irreversibly adsorbed on zirconia surface showed that perchlorated s amples are highly acidic up to a temperature of 250 degrees C, which drasti cally decreased on further heating. The material modified with perchlorate ion was found to be an efficient and selective catalyst for solvent-free mo nonitration of chlorobenzene. (C) 1999 Elsevier Science B.V. All rights res erved.